Weather Folklore: Fact or Fiction

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In mid-latitudes, a red sky in the evening indicates high-pressure systems and fair weather moving in.
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The soft-stemmed leaves of deciduous trees are easily flipped by strong winds, indicating a storm.
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Whether or not a groundhog sees his shadow has no bearing on future weather conditions.
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Birds fly lower in air with little density, which is caused by low pressure and moisture—both precursors of a storm.
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Contrary to lore, the coloration of a woolly bear caterpillar has to do with the weather of the recent past, not the future.
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Cirrostratus clouds reflect the light from the moon, making a halo visible in the sky and indicating precipitation is on its way.

Long before meteorologists existed, people forecasted the weather based on observations of daily conditions and the subsequent weather. Many of these forecasting methods became ingrained in our culture as “weather lore.” Today, we can examine these sayings and explain why they work — or don’t work — based on scientific study.

A few caveats: Just because a weather saying has a scientific basis doesn’t mean it’s accurate. Forecasts based on lore might prove correct only by chance or geography. For instance, if you say it’s going to be a cold winter, there’s a 50-50 chance you’ll be right!

“Red sky at night, sailor’s delight. Red sky at morning, sailor’s warning.”

This famous saying originates from the days of sailing and shepherding. A “red sky at night” would be to the west — a clearly visible sunset. This red sky might indicate dry air and clear skies. Such conditions typically accompany high pressure, and — with weather systems in mid latitudes tending to move from west to east — a continuation of fair weather. A “red sky at morning,” however, could imply that a protective high was moving away, allowing deteriorating weather to move in. There is some truth to this piece of lore, but it only works where weather moves from west to east.

“If the groundhog sees his shadow, there will be six more weeks of winter.”

Probably the most famous weather lore in the United States centers around Groundhog Day, which always falls on February 2. Legend has it that if Punxsutawney Phil sees his shadow (in other words, if it’s sunny), winter cold will continue into March; if he doesn’t (it’s cloudy), there will be an early spring. Our government has extensively studied this possibility. (To view their latest results, visit The National Centers for Environmental Information. My meteorologist wife maintains this page, by the way.) The conclusion is that you’d get just as accurate a long-range forecast from Bill Murray, star of the movie Groundhog Day.

“When leaves show their undersides, be very sure rain betides.”

Deciduous trees have leaves that curl or turn upward under conditions that precede a storm. When humidity is high, their soft stems grow limp, allowing strong winds to flip them easily. While this only works with deciduous trees, such as oak or poplar, it’s generally accurate.

“Clear moon, frost soon.”

Clear skies at night allow maximum radiational cooling, meaning heat absorbed during the day escapes from the Earth’s surface. With no clouds to trap the heat, this cooling is more rapid under skies so cloudless that the moon is clearly visible. During the spring or fall when temperatures drop at night, this can mean frost the next morning.

“Rain foretold, long last. Short notice, soon will pass.”

Major storm systems are often preceded by lowering and thickening clouds, as well as increasing winds, sometimes days in advance. Precipitation will likely last longer with such systems, as they’ve had time to develop. If the system develops quickly, however, such as the cumulus clouds that produce surprise showers, precipitation won’t last long.

“You can tell the temperature by counting a cricket’s chirps.”

If you count a cricket’s chirps for 14 seconds, then add 40, you’ll have the temperature of the cricket’s location in Fahrenheit, give or take a few degrees.

“When dew is on the grass, rain will never come to pass. When grass is dry at morning light, look for rain before the night.”

Dew tends to form on clear, calm nights when there’s maximum radiational cooling. Cloudy, windy nights are warmer with no dew, and clouds and wind can foretell rain. Weather situations change during the day, so this isn’t always accurate.

“When sound travels far and wide, a stormy day will betide.”

Sound waves travel best in humidity, as moist air is less dense than dry air. With less mass to move through, sound propagates faster and further. But since humidity doesn’t always signal rainfall, this lore may only be true alongside other conditions.

“If birds fly low, expect rain and a blow.”

When air pressure is high and the air is dry, the air itself is denser, which makes it easier for birds to fly higher in the sky. Lower pressure and moisture both lower the air density, and so birds fly lower. These conditions are also precursors of a storm

“Cows laying down, weather on the way.”

There’s proof that cows stand when they’re trying to cool off, and that they lie down to conserve body heat. As low pressure moves in before a storm, which is also a sign that the temperature will drop, it’s possible that cows react to the change and lie down. However, cows might lie down for up to 14 hours a day, and often rest in the shade on hot, fair days.

“Rainbow in morning, sailor take warning. Rainbow at night, sailor’s delight.”

Rainbows always occur on the opposite side of the sky from the sun, being produced on a curtain of rain droplets. A rainbow in the morning means there’s rain to the west, which is most likely moving toward you — but, as above, this is truest in mid latitudes. A rainbow in the evening means rain to the east, which is probably moving away from you.

“Tornadoes never strike big cities.”

Statistically, big cities aren’t hit by tornadoes as often as rural areas, but this is simply because cities don’t occupy much land. Sprawling urban cities are still specks on the map compared with the surrounding land. In addition, there are fewer big cities in tornado-prone areas. But that’s no guarantee — Joplin, Missouri, was hit in 2011 by a large, destructive tornado.

“If March comes in like a lion, it will go out like a lamb.”

This is a questionable forecast scheme. A warm start to March can be followed by colder weather, since there’s still cold air to the north. But while weather patterns do typically change over a period of 30 days, they can easily change back again.

“The longer the woolly bear’s black bands, the longer and colder the winter will be.”

Another legendary winter forecaster is the woolly bear, or, as it’s known in the South, the “woolly worm.” The body of this caterpillar is black on both ends and reddish-brown in the middle. According to legend, the narrower this reddish-brown middle band is in fall, the colder the upcoming winter. Actually, though, the caterpillar’s coloration has to do with the weather of the recent past and its subsequent growing season. A good growing season means more to eat, more growth on the ends of the caterpillar, and a relatively narrower middle band.

“Halo around the sun or moon, rain or snow soon.”

The halo (sometimes just called a circle or ring) is formed by cirrostratus clouds made of ice crystals, and these crystals reflect the light, making the halo visible. Because cirrostratus clouds often indicate a warm front that precedes oncoming storms, the ring around the sun or moon implies a higher probability that precipitation is on its way.

“Hair curls when the humidity is high.”

Human hair is extremely sensitive to changes in humidity. In fact, there are hygrometers (devices which indicate humidity) that use human hair as a measuring mechanism. Your hair can actually absorb water from the air through hydrogen bonds; because there’s more moisture in humid air, a strand of hair can form a higher number of hydrogen bonds. This causes hair to fold back on itself.

“Count the seconds between lightning and thunder to tell how far away a storm is.”

This is true. Light travels faster than sound. Count the seconds between viewing a flash of lightning and hearing the thunder; for every 5 seconds you count, the lightning is 1 mile away.

“Some people can ‘feel’ when bad weather is coming.”

Many people with chronic pain, especially those with arthritis, claim their pain increases with the approach of bad weather. Falling barometric pressure, increasing humidity, and lowering temperatures can affect joint pain, and also typically occur as a storm is approaching. Those sensitive to the weather may indeed be able to feel it changing.

Do you have any favorite weather folklore? If I missed it, let me know!

Ed Brotak taught thousands of college students about the weather for more than 30 years. He lives in Asheville, North Carolina, with his wife and two daughters, and he still goes outside when he hears thunder.

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